公开(公告)号：US12286681B2

公开(公告)日：2025-04-29

申请号：US17425112

申请日：2020-01-14

Applicant: JFE Steel Corporation

Inventor： Yuka Miyamoto ,  Yasuhiro Sakurai ,  Yoshihiko Ono

IPC: C21D9/46 ,  C21D6/00 ,  C21D6/04 ,  C21D8/02 ,  C22C38/00 ,  C22C38/02 ,  C22C38/04 ,  C22C38/06 ,  C22C38/10 ,  C22C38/20 ,  C22C38/22 ,  C22C38/26 ,  C22C38/28 ,  C22C38/46 ,  C22C38/54

Abstract: A high-carbon hot-rolled steel sheet and a method for manufacturing the steel sheet are provided. The high-carbon hot-rolled steel sheet has a particular chemical composition. The microstructure of the steel sheet includes ferrite, cementite, and pearlite that accounts for 6.5% or less of the entire microstructure by area fraction. The proportion of the number of cementite grains having an equivalent circle diameter of 0.1 μm or less to the total number of cementite grains is 20% or less, the average cementite grain size is 2.5 μm or less, and the cementite accounts for 1.0% or more and less than 3.5% of the entire microstructure by area fraction. The average concentration of solute B in a region extending from a surface layer to a depth of 100 μm is 10 mass ppm or more. The average concentration of N present as AlN in the region is 70 mass ppm or less.

公开(公告)号：US12123069B2

公开(公告)日：2024-10-22

申请号：US17286148

申请日：2019-10-16

Applicant: JFE STEEL CORPORATION

Inventor： Yoshihiko Ono ,  Junya Tobata ,  Hiroyuki Akimoto ,  Yoichiro Matsui ,  Shinjiro Kaneko

IPC: C21D9/46 ,  C21D1/20 ,  C21D6/00 ,  C21D8/02 ,  C22C38/00 ,  C22C38/02 ,  C22C38/04 ,  C22C38/06 ,  C22C38/12 ,  C22C38/14 ,  C22C38/42 ,  C22C38/44 ,  C22C38/50 ,  C22C38/54 ,  C22C38/58 ,  C22C38/60

CPC classification number: C21D9/46 ,  C21D1/20 ,  C21D6/004 ,  C21D6/005 ,  C21D6/008 ,  C21D8/0205 ,  C21D8/0226 ,  C21D8/0236 ,  C21D8/0263 ,  C22C38/001 ,  C22C38/002 ,  C22C38/005 ,  C22C38/02 ,  C22C38/04 ,  C22C38/06 ,  C22C38/12 ,  C22C38/14 ,  C22C38/42 ,  C22C38/44 ,  C22C38/50 ,  C22C38/54 ,  C22C38/58 ,  C22C38/60 ,  C21D2211/002 ,  C21D2211/005 ,  C21D2211/008

Abstract: A steel sheet having a specified chemical composition and a method for producing the steel sheet. The steel sheet has a microstructure comprising ferrite: 5% or less, and at least one of upper bainite, fresh martensite, tempered martensite, lower bainite, and retained γ: 95% to 100% by area percentage, and retained γ: 4% to 15% by volume percentage. Retained γUB has a specified area percentage SγUB, retained γLB has a specified distribution number NγLB, and at least one of (i) fresh martensite has a specified equivalent circular grain diameter and aspect ratio and (ii) retained γ grains has a specified equivalent circular grain diameter and aspect ratio.

公开(公告)号：US12077831B2

公开(公告)日：2024-09-03

申请号：US17415532

申请日：2019-10-25

Applicant: JFE STEEL CORPORATION

Inventor： Shimpei Yoshioka ,  Yoshihiko Ono ,  Yuma Honda ,  Nobuyuki Nakamura

IPC: C21D9/46 ,  B22D11/18 ,  C21D8/02 ,  C22C38/00 ,  C22C38/02 ,  C22C38/04 ,  C22C38/06 ,  C22C38/12 ,  C22C38/14 ,  C23C2/06

CPC classification number: C21D9/46 ,  B22D11/182 ,  C21D8/0226 ,  C21D8/0236 ,  C21D8/0273 ,  C22C38/001 ,  C22C38/002 ,  C22C38/02 ,  C22C38/04 ,  C22C38/06 ,  C22C38/12 ,  C22C38/14 ,  C23C2/06 ,  C21D2211/001 ,  C21D2211/002 ,  C21D2211/005 ,  C21D2211/008

Abstract: A steel sheet having a specified chemical composition and a tensile strength of 1,320 MPa or more, and methods for producing the steel sheet. The steel sheet has a specified microstructure including martensite and bainite, the total area fraction of the martensite and the bainite being 95% or more and 100% or less, the balance being one or more selected from ferrite and retained austenite. The forumulae [% Ti]+[% Nb]>0.007 and [% Ti]×[% Nb]2≤7.5×10−6 are satisfied in the chemical composition.

公开(公告)号：US11946112B2

公开(公告)日：2024-04-02

申请号：US17270613

申请日：2019-08-22

Applicant: JFE Steel Corporation

Inventor： Yoshihiko Ono ,  Yuma Honda ,  Shimpei Yoshioka ,  Koichi Taniguchi ,  Hiroshi Matsuda ,  Takeshi Murai ,  Nobuyuki Nakamura

IPC: C21D9/46 ,  C21D6/00 ,  C21D8/02 ,  C22C38/00 ,  C22C38/02 ,  C22C38/04 ,  C22C38/06 ,  C22C38/08 ,  C22C38/12 ,  C22C38/14 ,  C22C38/16 ,  C22C38/42 ,  C22C38/44 ,  C22C38/46 ,  C22C38/48 ,  C22C38/50 ,  C22C38/54 ,  C22C38/58 ,  C22C38/60 ,  C23C2/02 ,  C23C2/06 ,  C23C2/40

CPC classification number: C21D9/46 ,  C21D6/005 ,  C21D6/008 ,  C21D8/0205 ,  C21D8/0226 ,  C21D8/0236 ,  C21D8/0247 ,  C22C38/001 ,  C22C38/002 ,  C22C38/005 ,  C22C38/008 ,  C22C38/02 ,  C22C38/04 ,  C22C38/06 ,  C22C38/08 ,  C22C38/12 ,  C22C38/14 ,  C22C38/16 ,  C22C38/42 ,  C22C38/44 ,  C22C38/46 ,  C22C38/48 ,  C22C38/50 ,  C22C38/54 ,  C22C38/58 ,  C22C38/60 ,  C23C2/02 ,  C23C2/0224 ,  C23C2/024 ,  C23C2/06 ,  C23C2/40 ,  C21D2211/001 ,  C21D2211/002 ,  C21D2211/005 ,  C21D2211/008

Abstract: A high-strength steel sheet of the present invention has a specific chemical composition. Furthermore, in the steel sheet, a degree of Mn segregation in a specific region is 1.5 or less; a maximum P concentration in a specific region is 0.08 mass % or less; in a specific region, at least one specific MnS particle group is present, the number of specific MnS particle groups is 2.0 or fewer per 1 mm2, and the number of specific oxide-based inclusions is 8 or fewer per 1 mm2; of all oxide-based inclusions, oxide-based inclusions having a specific composition are present in a number ratio of 80% or greater; the microstructure includes, in terms of a volume fraction, 30 to 95% martensite, 5 to 70% ferrite phase, less than 30% (and 0% or greater) bainite, and less than 2.0% (and 0% or greater) austenite phase; and a tensile strength is 980 MPa or greater.

公开(公告)号：US11453926B2

公开(公告)日：2022-09-27

申请号：US16089846

申请日：2017-01-16

Applicant: JFE STEEL CORPORATION

Inventor： Tatsuya Nakagaito ,  Yoshimasa Funakawa ,  Yoshihiko Ono ,  Hiroshi Hasegawa

IPC: B32B15/01 ,  C21D9/46 ,  C21D6/00 ,  C21D8/02 ,  C22C38/00 ,  C22C38/02 ,  C22C38/06 ,  C22C38/12 ,  C22C38/14 ,  C22C38/38 ,  C23C2/06 ,  C23C2/28 ,  C23C2/40

Abstract: A steel sheet having excellent fatigue resistance as a material for automobile parts and a TS of 590 MPa or more, and a method for producing the same. The steel sheet having a specified chemical composition and a microstructure of 50% or more and 90% or less of martensite, 10% to 50% of ferrite and bainite in total, in terms of an area ratio, and an average concentration of solute Mn in ferrite in a region from a surface of a base steel to a depth of 0.5 μm is 60% or more relative to an average concentration of solute Mn in ferrite at a location of ¼ in the thickness of the steel sheet.

公开(公告)号：US20210340641A1

公开(公告)日：2021-11-04

申请号：US17271663

申请日：2019-08-22

Applicant: JFE Steel Corporation

Inventor： Yoshihiko Ono ,  Yuma Honda ,  Shimpei Yoshioka ,  Koichi Taniguchi ,  Nobuyuki Nakamura ,  Takeshi Murai

IPC: C21D9/46 ,  C21D8/02 ,  C21D6/00 ,  C21D6/02 ,  C22C38/58 ,  C22C38/60 ,  C22C38/54 ,  C22C38/50 ,  C22C38/48 ,  C22C38/42 ,  C22C38/16 ,  C22C38/14 ,  C22C38/12 ,  C22C38/08 ,  C22C38/04 ,  C22C38/02 ,  C22C38/00 ,  C22C38/06 ,  C23C2/06 ,  C23C2/40 ,  C23C2/02

Abstract: A high-strength steel sheet of the present invention has a specific chemical composition. Furthermore, in the steel sheet, a degree of Mn segregation in a specific region is 1.5 or less; a maximum P concentration in a specific region is 0.08 mass % or less; in a specific region, the number of specific MnS particle groups is 2.0 or fewer per 1 mm2, and the number of specific oxide-based inclusions is 8 or fewer per 1 mm2; of all of the oxide-based inclusions, oxide-based inclusions having a specified composition are present in a number ratio of 80% or greater; the microstructure includes, in terms of a volume fraction, 30 to 95% martensite and bainite in total, 5 to 70% ferrite phase, and less than 3% (and 0% or greater) austenite phase; and a tensile strength is 980 MPa or greater.

公开(公告)号：US11111553B2

公开(公告)日：2021-09-07

申请号：US16076381

申请日：2017-02-07

Applicant: JFE STEEL CORPORATION

Inventor： Yusuke Kimata ,  Yoshihiko Ono ,  Kenji Kawamura

IPC: C21D8/02 ,  C21D9/46 ,  C22C38/06 ,  C22C38/00 ,  C22C38/02 ,  C22C38/04 ,  C22C38/42 ,  C22C38/44 ,  C22C38/46 ,  C22C38/48 ,  C22C38/50 ,  C22C38/58 ,  C21D6/00 ,  C22C38/54

Abstract: A high-strength steel sheet having a tensile strength (TS) of 1,320 MPa or more and good workability. The high-strength steel sheet has a specific component composition and a steel microstructure containing, on an area-percentage basis with respect to the entire steel microstructure, 40% or more and less than 85% of a lower bainite, 5% or more and less than 40% martensite including tempered martensite, 10% or more and 30% or less retained austenite, and 10% or less (including 0%) polygonal ferrite, the retained austenite having an average C content of 0.60% by mass or more. Additionally, a Mn segregation value at a surface of the steel sheet is 0.8% or less, the ratio R/t of a limit bending radius (R) to a thickness (t) of the steel sheet is 2.0 or less, and tensile strength×total elongation of the steel sheet is 15,000 MPa % or more.

公开(公告)号：US11085099B2

公开(公告)日：2021-08-10

申请号：US15999603

申请日：2017-02-15

Applicant: JFE Steel Corporation

Inventor： Shimpei Yoshioka ,  Yoshihiko Ono ,  Hiroyuki Masuoka

IPC: C22C38/00 ,  C22C38/02 ,  C22C38/06 ,  C22C38/10 ,  C22C38/12 ,  C22C38/14 ,  C22C38/20 ,  C22C38/38 ,  C21D9/46 ,  C21D6/00 ,  C21D8/02 ,  C23G1/08

Abstract: A high-strength cold-rolled steel sheet has a composition that contains, in terms of mass %, C: 0.10% or more and 0.50% or less, Si: 1.0% or more and 3.0% or less, Mn: 1.0% or more and 2.5% or less, P: 0.05% or less, S: 0.02% or less, Al: 0.01% or more and 1.5% or less, N: 0.005% or less, Cu: 0.05% or more and 0.50% or less, and the balance being Fe and unavoidable impurities, wherein a proportion of a steel sheet surface covered with oxides mainly composed of Si is 1% or less, a proportion of the steel sheet surface covered with Fe oxides is 40% or less, CuS/CuB is 4.0 or less, and a tensile strength is 1180 MPa or more, when CuS denotes the Cu content in a steel sheet surface layer and CuB denotes the Cu content in a base material.

公开(公告)号：US20210010115A1

公开(公告)日：2021-01-14

申请号：US17042521

申请日：2019-03-29

Applicant: JFE Steel Corporation

Inventor： Hiromi Yoshitomi ,  Yoshihiko Ono ,  Tatsuya Nakagaito

IPC: C22C38/50 ,  C21D9/46 ,  C21D8/02 ,  C22C38/44 ,  C22C38/42 ,  C22C38/46 ,  C22C38/00 ,  C22C38/06 ,  C22C38/04

Abstract: A high-strength galvanized steel sheet of the present invention includes a steel sheet having a specific chemical composition, and a steel structure containing, in terms of area ratio, 4% or more and 20% or less of retained austenite, 30% or less (including 0%) of ferrite, 40% or more of martensite, and 10% or more and 50% or less of bainite; and a galvanized layer provided on the steel sheet, in which an amount of diffusible hydrogen in the steel is less than 0.20 mass ppm, a tensile strength is 1100 MPa or more, a relationship between a tensile strength TS (MPa), an elongation El (%), and a sheet thickness t (mm) satisfies a (1) formula below, and a yield ratio YR is 67% or more. TS×(El+3−2.5t)≥13000   (1)

公开(公告)号：US20200157647A1

公开(公告)日：2020-05-21

申请号：US16604398

申请日：2018-04-13

Applicant: JFE Steel Corporation

Inventor： Yoshihiko Ono ,  Junya Tobata ,  Hiroyuki Akimoto

IPC: C21D9/46 ,  C21D8/02 ,  C21D6/00 ,  C22C38/60 ,  C22C38/14 ,  C22C38/12 ,  C22C38/16 ,  C22C38/08 ,  C22C38/06 ,  C22C38/04 ,  C22C38/02 ,  C22C38/00

Abstract: A steel sheet and a manufacturing method therefor are provided.A steel sheet has a component composition and contains 6 to 80% of ferrite and 20 to 94% of a microstructure composed of one or two or more of upper bainite, fresh martensite, tempered martensite, lower bainite, and retained γ, and contains 7 to 20% of retained γ, where: an area ratio (SγUB) of retained γ having a particle width of 0.18 to 0.60 μm, a particle length of 1.7 to 7.0 μm, and an aspect ratio of 5 to 15 is 0.2 to 5%; and a total area ratio (SγBlock) of fresh martensite having an equivalent circle diameter of 1.5 to 15 μm and an aspect ratio of 3 or less and/or retained γ particles having an equivalent circle diameter of 1.5 to 15 μm and an aspect ratio of 3 or less is 3% or less (including 0%).